For a conventional cord controlled ceiling fan, a cord of the ceiling fan may be pulled by a user to change a gear ratio of a gearbox of the ceiling fan, thereby adjusting a rotary speed of a motor of the ceiling fan. The user has to be standing to reach and pull the cord each time he/she wants to adjust the rotary speed of the motor. This is inconvenient for the user, especially if the user is disabled or if the user (e.g., a child) is short.
In recent years, the conventional cord controlled ceiling fan may be modified to be wirelessly controlled by a remote controller. In the modified ceiling fan, a local controller is added, and is controlled by the remote controller to change a ratio by which a voltage is stepped down, thereby adjusting the rotary speed of the motor. Moreover, the gear ratio of the gearbox is fixed at its maximum, so that the voltage can be changed within a sufficiently large range; and as a consequence, the rotary speed of the motor cannot be adjusted by pulling the cord. In case the remote controller is lost, the user is unable to adjust the rotary speed of the motor.